- Tytuł:
- Optically induced coherent phonons in bismuth oxyiodide (BiOI) nanoplatelets
- Autorzy:
-
Fürmann, Tim
Rieger, Sebastian
Feldmann, Jochen
Stolarczyk, Jacek - Opis:
- Bismuth oxyiodide (BiOI) is a promising material for photocatalysis combining intriguing optical and structural properties. We show that excitation by a femtosecond laser pulse creates coherent phonons inducing a time-variant oscillating modulation of the optical density. We find that the two underlying frequencies originate from lattice vibrations along the [001] crystallographic axis, the stacking direction of oppositely charged layers in BiOI. This is consistent with a subpicosecond charge separation driven by a built-in dipolar field. This partially screens the field, launching coherent phonons. Further, we determine the two major dephasing mechanisms that lead to the loss of vibronic coherence: (i) the anharmonic decay of an optical phonon into two acoustic phonons and (ii) phonon-carrier scattering. Our results provide a direct demonstration of the presence of an electric field in BiOI along the [001] axis and show its role in efficient charge separation that is crucial for photocatalytic applications of BiOI.
- Dostawca treści:
- Repozytorium Uniwersytetu Jagiellońskiego
Artykuł